Revised July 2019
What is medical marijuana?
The term medical marijuana refers to using the whole, unprocessed marijuana plant or its basic extracts to treat symptoms of illness and other conditions. The U.S. Food and Drug Administration (FDA) has not recognized or approved the marijuana plant as medicine.
However, scientific study of the chemicals in marijuana, called cannabinoids, has led to two FDA-approved medications that contain cannabinoid chemicals in pill form. Continued research may lead to more medications.
Because the marijuana plant contains chemicals that may help treat a range of illnesses and symptoms, many people argue that it should be legal for medical purposes. In fact, a growing number of states have legalized marijuana for medical use.
Why isn’t the marijuana plant an FDA-approved medicine?
The FDA requires carefully conducted studies (clinical trials) in hundreds to thousands of human subjects to determine the benefits and risks of a possible medication. So far, researchers haven't conducted enough large-scale clinical trials that show that the benefits of the marijuana plant (as opposed to its cannabinoid ingredients) outweigh its risks in patients it's meant to treat.
Read more about the various physical, mental, and behavioral effects of marijuana in our Marijuana DrugFacts.
Medical Marijuana Laws and Prescription Opioid Use Outcomes
A new study underscores the need for additional research on the effect of medical marijuana laws on opioid overdose deaths and cautions against drawing a causal connection between the two. Early research suggested that there may be a relationship between the availability of medical marijuana and opioid analgesic overdose mortality. In particular, a NIDA-funded study published in 2014 found that from 1999 to 2010, states with medical cannabis laws experienced slower rates of increase in opioid analgesic overdose death rates compared to states without such laws.1
A 2019 analysis, also funded by NIDA, re-examined this relationship using data through 2017. Similar to the findings reported previously, this research team found that opioid overdose mortality rates between 1999-2010 in states allowing medical marijuana use were 21% lower than expected. When the analysis was extended through 2017, however, they found that the trend reversed, such that states with medical cannabis laws experienced an overdose death rate 22.7% higher than expected.2 The investigators uncovered no evidence that either broader cannabis laws (those allowing recreational use) or more restrictive laws (those only permitting the use of marijuana with low tetrahydrocannabinol concentrations) were associated with changes in opioid overdose mortality rates.
These data, therefore, do not support the interpretation that access to cannabis reduces opioid overdose. Indeed, the authors note that neither study provides evidence of a causal relationship between marijuana access and opioid overdose deaths. Rather, they suggest that the associations are likely due to factors the researchers did not measure, and they caution against drawing conclusions on an individual level from ecological (population-level) data. Research is still needed on the potential medical benefits of cannabis or cannabinoids.
Read more in our Marijuana Research Report.
What are cannabinoids?
Cannabinoids are chemicals related to delta-9-tetrahydrocannabinol (THC), marijuana’s main mind-altering ingredient that makes people "high." The marijuana plant contains more than 100 cannabinoids. Scientists as well as illegal manufacturers have produced many cannabinoids in the lab. Some of these cannabinoids are extremely powerful and have led to serious health effects when misused. Read more in our Synthetic Cannabinoids (K2/Spice) DrugFacts.
The body also produces its own cannabinoid chemicals. They play a role in regulating pleasure, memory, thinking, concentration, body movement, awareness of time, appetite, pain, and the senses (taste, touch, smell, hearing, and sight).
Are People with Health- and Age-Related Problems More Vulnerable to Marijuana’s Risks?
State-approved medicinal use of marijuana is a fairly new practice. For that reason, marijuana’s effects on people who are weakened because of age or illness are still relatively unknown. Older people and those suffering from diseases such as cancer or AIDS could be more vulnerable to the drug’s harmful effects, but more research is needed.
How might cannabinoids be useful as medicine?
Currently, the two main cannabinoids from the marijuana plant that are of medical interest are THC and CBD.
THC can increase appetite and reduce nausea. THC may also decrease pain, inflammation (swelling and redness), and muscle control problems.
Unlike THC, CBD is a cannabinoid that doesn't make people "high." These drugs aren't popular for recreational use because they aren't intoxicating. It may be useful in reducing pain and inflammation, controlling epileptic seizures, and possibly even treating mental illness and addictions. The FDA approved a CBD-based liquid medication called Epidiolex® for the treatment of two forms of severe childhood epilepsy, Dravet syndrome and Lennox-Gastaut syndrome.
Many researchers, including those funded by the National Institutes of Health (NIH), are continuing to explore the possible uses of THC, CBD, and other cannabinoids for medical treatment.
For instance, recent animal studies have shown that marijuana extracts may help kill certain cancer cells and reduce the size of others. Evidence from one cell culture study with rodents suggests that purified extracts from whole-plant marijuana can slow the growth of cancer cells from one of the most serious types of brain tumors. Research in mice showed that treatment with purified extracts of THC and CBD, when used with radiation, increased the cancer-killing effects of the radiation.3
Scientists are also conducting preclinical and clinical trials with marijuana and its extracts to treat symptoms of illness and other conditions, such as:
diseases that affect the immune system, including:
- multiple sclerosis (MS), which causes gradual loss of muscle control
- substance use disorders
- mental disorders
Read more about the NIH’s marijuana research:
Using Medical Marijuana During and After Pregnancy
Some women report using marijuana to treat severe nausea they have during pregnancy. But there's no research that shows that this practice is safe, and doctors generally don't recommend it.
Pregnant women shouldn't use medical marijuana without first checking with their health care provider. Animal studies have shown that moderate amounts of THC given to pregnant or nursing women could have long-lasting effects on the child, including abnormal patterns of social interactions4 and learning issues.5,6 Read more in our Substance Use in Women Research Report.
What medications contain cannabinoids?
Two FDA-approved drugs, dronabinol and nabilone, contain THC. They treat nausea caused by chemotherapy and increase appetite in patients with extreme weight loss caused by AIDS. Continued research might lead to more medications.
The United Kingdom, Canada, and several European countries have approved nabiximols (Sativex®), a mouth spray containing THC and CBD. It treats muscle control problems caused by MS, but it isn't FDA-approved.
Points to Remember
- The term medical marijuana refers to treating symptoms of illness and other conditions with the whole, unprocessed marijuana plant or its basic extracts.
- The FDA has not recognized or approved the marijuana plant as medicine.
- However, scientific study of the chemicals in marijuana called cannabinoids has led to two FDA-approved medications in pill form, dronabinol and nabilone, used to treat nausea and boost appetite.
- Cannabinoids are chemicals related to delta-9-tetrahydrocannabinol (THC), marijuana’s main mind-altering ingredient.
- Currently, the two main cannabinoids from the marijuana plant that are of interest for medical treatment are THC and cannabidiol (CBD).
- The body also produces its own cannabinoid chemicals.
- Scientists are conducting preclinical and clinical trials with marijuana and its extracts to treat symptoms of illness and other conditions.
For more information about marijuana and its health effects, visit our:
- Bachhuber MA, Saloner B, Cunningham CO, Barry CL. Medical cannabis laws and opioid analgesic overdose mortality in the United States, 1999-2010. JAMA Intern Med. 2014;174(10):1668-1673. doi:10.1001/jamainternmed.2014.4005
- Chelsea L. Shover, Corey S. Davis, Sanford C. Gordon, and Keith Humphreys, Association between medical cannabis laws and opioid overdose mortality has reversed over time, PNAS June 25, 2019 116 (26) 12624-12626.
- Scott KA, Dalgleish AG, Liu WM. The combination of cannabidiol and Δ9-tetrahydrocannabinol enhances the anticancer effects of radiation in an orthotopic murine glioma model. Mol Cancer Ther. 2014;13(12):2955-2967. doi:10.1158/1535-7163.MCT-14-0402
- Trezza V, Campolongo P, Cassano T, et al. Effects of perinatal exposure to delta-9-tetrahydrocannabinol on the emotional reactivity of the offspring: a longitudinal behavioral study in Wistar rats. Psychopharmacology (Berl). 2008;198(4):529-537.doi:10.1007/s00213-008-1162-3
- Antonelli T, Tomasini MC, Tattoli M, et al. Prenatal exposure to the CB1 receptor agonist WIN 55,212-2 causes learning disruption associated with impaired cortical NMDA receptor function and emotional reactivity changes in rat offspring. Cereb Cortex N Y N 1991. 2005;15(12):2013-2020. doi:10.1093/cercor/bhi076
- Mereu G, Fà M, Ferraro L, et al. Prenatal exposure to a cannabinoid agonist produces memory deficits linked to dysfunction in hippocampal long-term potentiation and glutamate release. Proc Natl Acad Sci U S A. 2003;100(8):4915-4920.doi:10.1073/pnas.0537849100
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Cite this article
NIDA. (2019, July 5). Marijuana as Medicine. Retrieved from https://www.drugabuse.gov/publications/drugfacts/marijuana-medicine
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